Small but Perfectly Formed #3

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Just in case anyone thinks this has turned into ‘Darren’s Insanity and Humour’ blog, here is a geeky plant post:

Lithops (‘Living Stones’).

I’m sure you have all seen these and maybe even grown them, though many people struggle to flower them (the flowers are either white or yellow – see below).

What I wanted to highlight in this post is their seed distribution mechanism which involves a startling amount of movement for a plant that seemingly never changes.

After pollination (they are not self-fertile so need another Lithops plant to supply pollen) the woody and tough protective seed capsule takes up to a year to ripen and is ready to shed seed at around the same time the plant produces the following years flowers. This is in late summer or autumn when the very arid habitat is most likely to receive rain to give the young seedlings a chance of surviving.

So – how does the plant ‘know’ to release the seeds at the optimum time? It uses the rain as a trigger.

The first raindrop landing on a capsule causes the top of the capsule to fold back and open rather like the eggs in Alien! Subsequent raindrops then wash the seeds from the capsule and water them into the surrounding soil.

This is clever enough in itself but some members of this family also have inner structures in the capsule that prevent all the seeds from being washed out at once – giving the plant another chance if the first lot to be released do not survive – often because the rains were too brief. Even then the story does not end – some species even have further seeds partially embedded in the capsule walls and these only get released when the capsule rots or is abraded by the wind – sometimes years after pollination.

The capsule opening takes only seconds – the two pictures below were taken only a minute apart before and after I splashed water on the plant.

pretty hard actually, especially the top. Cool to the touch too, just like a pebble. When not in flower they are very hard to see in the wild. The lines on the top are often actually transparent windows that allow light through to the photosynthetic cells beneath. A fingernail would make a cut but they are surprisingly tough.

Thank you Sophie. I am OK thanks. V tired as I have worked over 12 hours most days this week and the flooding in our area has made the commute long and unpleasant. I am so pleased it is friday! 😀 Been enjoying your posts on your trip to China.

Thank you Ellie. Looking at my plant collection as a whole it is clear to me that I have a thing for plants with weird adaptations to hostile environments. There is probably some deep seated psychological reason for this!

Thank you Roda. They’d probably do ok in your hoop house! They need a cool and totally dry winter and will stand a few degrees of frost if dry. They need hardly any water even in growth and I will not water mine again now until June. Then they get watered only once or twice a month until october.

I have finished the logo but need to photograph it for you! I have the whole weekend to myself as Susan is staying with her sister specifically to give me some peace after I have had an exhausting week. So I hope to get the photos and lots of other things done.

Exactly the right thing to do Linda. Yours are obviously happy if they flower. I know growers in the uk who only water Lithops four times per year. One a month from july to october. But then we have high humidity so little extra water is needed.